This article includes discussion of hypoparathyroidism, pseudohypoparathyroidism, and pseudopseudohypoparathyroidism. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.

Overview

Hypoparathyroidism is an endocrine deficiency disease resulting from decreased function of the parathyroid glands, with underproduction of parathyroid hormone (PTH). Hypoparathyroidism typically presents with manifestations of hypocalcemia. Affected individuals can experience perioral and acral paresthesias, muscle cramps (especially carpopedal spasms), tetany, and seizures, but many also report fatigue, chronic headaches, insomnia, bone pain, and crampy abdominal pain. Symptomatic hypocalcemia can be a medical emergency requiring acute intravenous administration of calcium gluconate. Patients with hypoparathyroidism may also present with neurologic dysfunction related to ectopic brain calcification. Causes of hypoparathyroidism include surgery, autoimmune disorders, genetic diseases, hemochromatosis, magnesium deficiency, and idiopathic causes. The differential diagnosis includes hypomagnesemia, vitamin D deficiency, pseudohypoparathyroidism, and pseudopseudohypoparathyroidism. The primary goals of chronic management are to maintain calcium and phosphorus levels within acceptable limits. Current treatment options for chronic management include oral calcium, vitamin D, and thiazide diuretics. Teriparatide, a recombinant N-terminal fragment of PTH, has full biological activity; it is given by injection, and pump delivery emulates physiologic PTH replacement therapy.

Key points

• Hypoparathyroidism is an uncommon endocrine deficiency disease resulting from decreased function of the parathyroid glands, with underproduction of parathyroid hormone (PTH).

• Primary hypoparathyroidism results from a disorder of the parathyroid glands, whereas, in contrast, secondary hypoparathyroidism is a physiologic state in which PTH levels are low in response to a primary process that causes hypercalcemia.

• Hypoparathyroidism typically presents with manifestations of hypocalcemia because this interferes with normal muscle contraction and nerve conduction.

• The differential diagnosis of hypoparathyroidism includes hypomagnesemia, vitamin D deficiency or hereditary insensitivity to this vitamin, pseudohypoparathyroidism, and pseudopseudohypoparathyroidism.

• Hypoparathyroidism is the last endocrine deficiency disease for which treatment with the missing hormone is not standard therapy.

• Teriparatide, a recombinant N-terminal fragment of PTH (ie, PTH 1-34), has full biological activity; like insulin, it is given by injection, and pump delivery emulates physiologic PTH replacement therapy.

• The primary goals of chronic management are to maintain calcium and phosphorus levels within acceptable limits.

• Current treatment options for chronic management include oral calcium, vitamin D (including its metabolites and analogs), and thiazide diuretics.

Historical note and terminology

Hypoparathyroidism is an uncommon endocrine deficiency disease resulting from decreased function of the parathyroid glands, with underproduction of parathyroid hormone (PTH). This can lead to hypocalcemia and associated cramping, muscle twitching, or tetany. The condition can result from surgery of the neck (especially of the thyroid or parathyroid glands) or from immunologic, genetic, or other rare causes.

Primary hypoparathyroidism results from a disorder of the parathyroid glands. Secondary hypoparathyroidism is a physiologic state in which PTH levels are low in response to a primary process that causes hypercalcemia. This article will address primary hypoparathyroidism.

The history of our understanding of the parathyroid glands is detailed in the MedLink article, “Hypercalcemia.” In 1929 American endocrinologist Fuller Albright (1900–1969) and colleague Read McLane Ellsworth (1899–1970) diagnosed the first reported case of idiopathic hypoparathyroidism (Albright and Ellsworth 1929). Albright and colleagues later described pseudohypoparathyroidism and pseudopseudohypoparathyroidism (Albright et al 1942; Albright et al 1952).

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